I'm a CPA, did my own lease vs purchase last fall for my CTS V, decided to purchase based on my interpretation of all the facts and figures. While there wasn't a huge gap, and I got an excellent leasing price on a loaded '13 wagon, the purchase was cheaper in the long run. I've seen and read many posts where people justify either a purchase or lease because they own a business. Beware that a 100% business deduction of a lease payment or vehicle purchase is generally hard to support, especially for a luxury car. Unless you're parking the V at your office and keeping a strict odometer log supported by names/dates/places traveled, you'd be hard pressed to convince the IRS agent that you have 100% business use. There almost always is a personal use factor, which I recommend that everyone do their homework on. Luxury cars can be subject to much stricter review in my experience. Leasing generally works well for high dollar vehicles that consume a lot of cash to purchase, but factors like residuals, interest rates, etc should be considered. I'd suggest having a conversation with your CPA/tax professional prior to making a final decision.
Lease with accelerated payments so the car has a residual payoff cost of @10,000.00 after 3 yrs. That way you can right off the car as a lease in 3 years and buy it for the residual cas value at the end.